Bedbugs Foiled by Hairy Limbs, Study Finds

December 15, 2011

By CARRIE GANN

Want to fight bedbugs? Try giving your razor a rest.

A group of British researchers have found that hairier humans may have the upper hand in fending off bedbugs compared to their shaved peers. In a new study, scientists suggest that the fine hairs on human skin slow bedbugs down and help people better detect the bloodsuckers on their bodies.

Scientists at the University of Sheffield unleashed hungry bedbugs on the arms of 29 student volunteers, each with one shaved and one unshaved arm. The researchers watched the bedbugs, timing how long it took them to find a place to dig in for a meal. (None of the volunteers were actually bitten during the experiment; the researchers removed the bugs just as they were about to feed.) The volunteers kept a count of each time they felt a bug crawling on their skin.

They found that the volunteers detected the bugs more frequently on their hairy arms, and that the bedbugs on these hairy arms took longer to find a spot to bite.

The study was published in the journal Biology Letters.

Catherine Hill, a medical entomologist at Purdue University, said it made sense that more hair would slow down foraging bedbugs.

"But it's a bit counterintuitive that the host has a greater number of bedbug detections when there's more hair," Hill told ABC News. "But in a way, it makes sense. Hair is like our antennae, and it initiates a response from us by sending signals to our nervous system."

However, extreme hairiness could end up being a hindrance in the hunt for bedbugs, said the study's author, Michael Siva-Jothy.

"If you have a heavy coat of long, thick hairs, it is easier for parasites to hide, even if you can detect them," Siva-Jothy told BBC News.

Researchers said the study also gave interesting clues into how people evolved, with less hair on their bodies, than their hairier mammalian brethren. Previous research suggested that mosquitoes, bedbugs and other bloodsucking insects bit primarily on bare skin, such as wrists and ankles, of mammals and birds and navigated less frequently to the furry or feathery parts. It might be that humans with less hair were more able to find and remove unhealthy parasites, lowering their chances of catcing diseases from the bugs.

Bedbug infestations have been on the rise around the world, and U.S. exterminators are treating more of them than ever before, according to a 2011 survey from the National Pest Management Association. The bugs are about the size and color of a flat apple seed, and are found not only on mattresses and upholstery, but in suitcases, boxes, shoes, wallpaper and headboards.